Automation for milking animals, such as cows, is disclosed in numerous published articles and prior art patents.
For example, European Patent Application No. 0 385 539 discloses a system wherein animals can approach and be received by a milking robot freely for milking; in contrast to conventional milking, wherein the animal are, within a short period of time, usually milked twice a day, the automatic milking occurring randomly, spread over the day. Thus, a shorter or longer period may occur between two milkings of the same animal. The milk is stored in a refrigerated bulk milk tank. After the tank has been cleaned, or in any event has been emptied, there is a danger that when milk is next received in the tank it will be over-cooled and frozen.
British Patent Specification No. GB-A-1 266 870, which relates to a bulk milk tank, mentions the problem of milk freezing. As a solution, this document suggests to switch on, automatically, a further cooling element within the tank when milk in the tank has reached a certain level. This is accomplished by a sensing device, comprising a probe for sensing the level of the milk in the tank causing a further refrigerating unit to operate under the control of a thermostat. Further units are brought into operation as the corresponding refrigerated plates in the tank become substantially submerged in the milk. This British Patent Specification does not deal with the problem of milk being over-cooled when it initially enters an empty bulk milk tank nor does it reveal how and when the first cooling element of the tank is put into operation.
Therefore, although the dairy farm industry has long recognized the need to chill the milk obtained by a milking robot, under certain circumstances, known cooling processes do not perform satisfactory in that the milk may be over-cooled or frozen.